Post by weaselexpress on Jan 1, 2024 2:27:26 GMT -5
I recently installed a 70cc Malossi big bore kit on my scoot. I longed for a bit more speed. Before I installed the kit it was doing 65km/hr on the flat, 13,000km scooter IMO was running quite well for what I consider a shitbox.
After installing the kit I was able to get it to start and performed a few heat cycles to break the new top end in. jetted to 95 it started first kick but was unable to rev beyond about 5000rpm. I tried adjusting the jetting and went down to an 85, this somewhat improved the issue but bike was absolutely gutless. I only rode a few km's with this jetting as I was also afraid of running lean and blowing the engine.
Removed the stock airbox and did a test with no filter. Ran much nicer was able to rev up the full range however full rev not full throttle.
Replaced stock airbox with a large mesh box covered in filter foam, stock airbox snorkel goes straight from the carb into this box.
I rejetted to 115 and installed a new much higher flow filter. Now it actually runs well enough that I can ride it. however it dies immediately at about 60% throttle, go beyond 60% at any rev or speed and it will immediately die and wont come back until throttle is completely backed off.
Just took it for a ride with jets in my pocket to hopefully iron this out. First adjusted the carb clip from middle to leanest possible for 115 jet, ran much better but still died at 60% throttle. ended up down at 105 jet (going through all clip positions for each jet) and still every time died at 60% throttle.
I've got no clue what is going on. I suspect maybe the vacuum fuel petcock isn't allowing enough fuel and its starving but its an instant death beyond 60% throttle seems too quick to be fuel starvation. Running a naraku aftermarket CDI and recently replaced the coil so can be sure that everything regarding making spark is fine (although haven't tried replacing the sparkplug). Worth noting I have adjusted nothing in the variator since 50cc.
Each time I changed the jetting also adjusted the idle mixture screw however I suck at this so it was nothing more than a quick and dirty adjustment
Anyone else who is running a BBK what jetting are you running?
Any help would be much appreciated!
Planning to do some stationary tests this arvo and see if I can get the throttle to go beyond 60%. Will also try replacing the sparkplug with my one spare as my current sparkplug is more carbon than plug. Will update with results of tests.
After installing the kit I was able to get it to start and performed a few heat cycles to break the new top end in. jetted to 95 it started first kick but was unable to rev beyond about 5000rpm. I tried adjusting the jetting and went down to an 85, this somewhat improved the issue but bike was absolutely gutless. I only rode a few km's with this jetting as I was also afraid of running lean and blowing the engine.
Removed the stock airbox and did a test with no filter. Ran much nicer was able to rev up the full range however full rev not full throttle.
Replaced stock airbox with a large mesh box covered in filter foam, stock airbox snorkel goes straight from the carb into this box.
I rejetted to 115 and installed a new much higher flow filter. Now it actually runs well enough that I can ride it. however it dies immediately at about 60% throttle, go beyond 60% at any rev or speed and it will immediately die and wont come back until throttle is completely backed off.
Just took it for a ride with jets in my pocket to hopefully iron this out. First adjusted the carb clip from middle to leanest possible for 115 jet, ran much better but still died at 60% throttle. ended up down at 105 jet (going through all clip positions for each jet) and still every time died at 60% throttle.
I've got no clue what is going on. I suspect maybe the vacuum fuel petcock isn't allowing enough fuel and its starving but its an instant death beyond 60% throttle seems too quick to be fuel starvation. Running a naraku aftermarket CDI and recently replaced the coil so can be sure that everything regarding making spark is fine (although haven't tried replacing the sparkplug). Worth noting I have adjusted nothing in the variator since 50cc.
Each time I changed the jetting also adjusted the idle mixture screw however I suck at this so it was nothing more than a quick and dirty adjustment
Anyone else who is running a BBK what jetting are you running?
Any help would be much appreciated!
Planning to do some stationary tests this arvo and see if I can get the throttle to go beyond 60%. Will also try replacing the sparkplug with my one spare as my current sparkplug is more carbon than plug. Will update with results of tests.